1. Field of the Invention
This invention relates generally to an apparatus for warming a site on a body part of a human in preparation for a medical procedure. More specifically, the invention relates to a disposable apparatus for warming the heel or foot of a newborn prior to lancing thereof to obtain a blood sample.
2. State of the Art
Hospitals perform numerous blood tests on newborns, generally termed xe2x80x9cneonatesxe2x80x9d, being defined as infants less than one month old. Because of the difficulty and danger of venepuncture in newborns, a preferred method of collecting a blood sample from a newborn is to lance or puncture the heel to a relatively shallow depth, on the order of 2 to 4 mm. This procedure is commonly termed a xe2x80x9cheel stickxe2x80x9d. However, the heel stick skin puncture does not cause the blood to flow freely. Thus, the clinician may be tempted to squeeze the heel or perform a second stick to obtain a better sample. While application of minimal pressure to the puncture site may be tolerated, xe2x80x9cmilkingxe2x80x9d, or massaging, the puncture site can cause hemolysis and contaminates the resulting blood sample with interstitial and intercellular fluid. Similarly, squeezing the heel causes bruising, evidencing hemorrhaging and creating fibrin deposits, both of which compromise the affected area of the heel for resampling at a later time.
Heel punctures in newborns may result in Calcaneal Osteomyelitis, a serious complication, and thus minimizing the number of skin punctures has been deemed imperative by practitioners in the field. In hospitals, newborns are by far the most frequently tested patients, with blood tests being repeated periodically in an average of over 79% of cases. The repetition percentage rises to 98% when blood gases must be monitored. Risks of infection as well as cartilage damage associated with repeated sampling could be decreased by reducing the number of skin punctures required to collect an adequate sample.
It is known that warming the skin in an area to be punctured increases capillary action by dilating the blood vessels and consequently increases the rate of blood flow to the target area. Therefore, a newborn""s heel is typically warmed prior to a heel stick to increase the ease with which a blood sample is collected. The CPCC unanimously recommends warming of the site prior to puncture and, when collection of blood gases is the object of the procedure, have deemed prewarming to be xe2x80x9cessentialxe2x80x9d. The National Committee for Clinical Laboratory Standards specifically lists warming of the puncture site as part of the skin puncture procedure, as does the Handbook of Phlebotomy. Hospitals throughout the United States almost universally practice prewarming of an intended puncture site when dealing with neonatal infants.
Various warming devices in the form of disposable heat packs usable to warm an infant""s heel are known in the art. For example, see U.S. Pat. No. 5,143,048 to Cheney, U.S. Pat. No. 5,184,613 to Mintz, U.S. Pat. No. 5,305,733 to Walters and U.S. Pat. No. 5,800,492 to Manker. The Mintz device is formed in a symmetrical, wide, hourglass shape to facilitate wrapping of one portion of the pack about the leg and the otherabout the foot of the patient and to completely encircle both the foot and lower leg. The symmetrical design is also purported to make the device easier to apply, there being purportedly no xe2x80x9cwrong wayxe2x80x9d to position it. However, the Mintz device does not concentrate heat in the area to be prewarmed and its symmetrical shape and great width renders it unduly bulky, difficult to apply, uncomfortable for the infant and susceptible to loosening on an active infant.
Thus, it would be advantageous to provide a disposable heel warmer of a design which localizes heat in the target area for a skin puncture, easily conforms to the foot, may be securely affixed thereto, and easily removed therefrom for performance of a skin puncture after prewarming.
The present invention comprises a disposable warming device, asymmetrically longitudinally configured for ease of application to, conformance to, and subsequent removal from, the foot of a human patient, typically a neonatal infant.
A warming device according to one embodiment of the present invention includes an elongated pouch containing a selectively initiable heat source therein and comprising first and second segments. The two segments are in communication within the pouch through a neck region of reduced lateral width defined by notches extending laterally inwardly from sidewalls of the first and second segments. The first segment is relatively longer than the second segment, and each segment has associated therewith structure for independently securing it to a body portion of a human.
In one embodiment, the structure for independently securing the pouch segments to the body portion comprises two straps, each extending transversely to a longitudinal axis of the pouch, secured to a segment by a proximal portion of the strap and including an adhesive area thereon at a distal portion thereof, a medial portion of each strap being adhesive-free. Each strap may optionally include a perforation line extending transversely thereacross to facilitate removal of the warming device after use. The warming device pouch may be formed of film of polymer or other suitable material folded upon itself and subsequently heat sealed about three sides thereof to contain the heat source therein, the fourth side comprising the fold line. Alternatively, the warming device pouch may be formed of two superimposed film segments and heat sealed about its entire periphery.
Also disclosed is a method of warming the heel of an infant comprising providing a warming device comprising an elongated pouch having a longitudinal axis, placing a first, relatively longer segment of the pouch under a foot of an infant to the heel thereof and placing a second, relatively shorter segment of the pouch over the ankle of the foot by folding the pouch along a line extending substantially between notched areas on opposing sides of the pouch, and separately securing the first segment at least about a bottom and sides of the foot and the second segment about the ankle.
While the present invention has utility as a heel warmer for newborns, it may be used in for older children and adults as well. The present invention is believed to have specific utility for geriatric patients, whose circulatory systems are often impaired. The present invention may be fabricated in a larger size, as necessary or desirable. Further, although the present invention is described herein for use on the heel of a patient, it will be appreciated that the present invention may be used to warm any body part, especially prior to initiating an IV or drawing blood.